Conventionally, a motor vehicle dashboard contains at least one duct for air distribution, which is arranged to be supplied with a stream of processed air from an apparatus for heating and ventilation, and/or air conditioning, and to deliver this processed air to various vents which are located in selected positions in the cabin of the vehicle. The vents usually consist of de-icing vents for de-icing and demisting of the windshield, and often also the front side windows of the vehicle. The vents also usually include vents disposed on the front of the dashboard, including side vents and at least central vent, for the purpose of supplying ventilating air to the cabin.
Most vehicle dashboard of known types contain a plurality of air ducts, which are generally made of plastics material and which are interposed between the heating and ventilating (and/or air conditioning) apparatus and the various vents. The de-icing and demisting vents are usually supplied with air through ducts of plastics material which are secured below the armature of the moulded dashboard, and which are connected to a diffuser, again of plastics material, which is also fixed under the armature of the dashboard, the diffuser being arranged to be connected to the outlet of the heating and ventilating (and/or air conditioning) apparatus.
Similarly, the ventilating air vents are generally supplied with air through further ducts, again of plastics material, which are assembled together mechanically and fixed under the armature of the dashboard, these ducts being connected to another diffuser.
Thus, diffusion of the air within the known types of dashboard makes it necessary to provide a multiplicity of air ducts and duct connections which are interposed between the heating and ventilating (and/or air conditioning) apparatus and the various outlet vents. This leads to a number of disadvantages, and in particular the possibility of leaks at various joints, air noise due to vibration of the walls of the ducts, heat losses, aerodynamic losses, the need to provide a large number of components, occupation of large amount of space within the dashboard, and finally the fact that the fitting procedure is both long and complicated. These various disadvantages result in high manufacturing cost and operational inefficiency.
It is also known, from German patent specification No. DE-3 818 666, to provide a vehicle dashboard in which an air distribution duct is incorporated in the dashboard itself. This duct is made in the form of a single component which is fixed on the top of the dashboard. This known arrangement does reduce the number of components required, but at the same time still has most of the disadvantages listed above.
Up to the present time all attempts to make a dashboard which incorporates one or more air ducts in the dashboard itself have been unsuccessful, due in particular to the problems involved in operations of moulding the hollow parts, the shapes of which are complex.